In Newly Created Life-Form, a Major Mystery | Quanta Magazine

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The researchers had expected some number of unknown genes in the mix, perhaps totaling five to 10 percent of the genome. With 517 genes and 580,000 DNA letters, it has one of the smallest known genomes in a self-replicating organism.

M. genitalium’s trim package of DNA raised the question: What is the smallest number of genes a cell could possess? “We wanted to know the basic gene components of life,” Venter said.

What’s left after trimming the genetic fat? The majority of the remaining genes are involved in one of three functions: producing RNA and proteins, preserving the fidelity of genetic information, or creating the cell membrane.

Scientists can broadly classify 70 of them based on the genes’ structure, but the researchers have little idea of what precise role the genes play in the cell. Venter’s team is eager to figure out what the mystery genes do, but the challenge is multiplied by the fact that these genes don’t resemble any other known genes.

One way to investigate their function is to engineer versions of the cell in which each of these genes can be turned on and off.